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bioRxiv · 10.1101/724823

Evolving a new protein-DNA interface via sequential introduction of permissive and specificity-switching mutations

Jalal, A. S. B.·Tran, N. T.·Stevenson, C. E.·Tan, X.·Lawson, D. M.·Le, T. B. K.
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Abstract

Specific interactions between proteins and DNA are essential to many biological processes. Yet it remains unclear how the diversification in DNA-binding specificity was brought about, and what were the mutational paths that led to changes in specificity. Using a pair of evolutionarily related DNA-binding proteins, each with a different DNA preference (ParB and Noc: both having roles in bacterial chromosome maintenance), we show that specificity is encoded by a set of four residues at the protein-DNA interface. Combining X-ray crystallography and deep mutational scanning of the interface, we suggest that permissive mutations must be introduced before specificity-switching mutations to reprogram specificity, and that mutational paths to a new specificity do not necessarily involve dual-specificity intermediates. Overall, our results provide insight into the possible evolutionary history of ParB and Noc, and in a broader context, might be useful in understanding the evolution of other classes of DNA-binding proteins.

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Jalal, A. S. B., Tran, N. T., Stevenson, C. E., Tan, X., Lawson, D. M., Le, T. B. K.. 2019-08-05. Evolving a new protein-DNA interface via sequential introduction of permissive and specificity-switching mutations. https://doi.org/10.1101/724823

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